Ions and Ionic Bonding

Think of ions as atoms that have either lost or gained electrons, giving them an electric charge. When a metal atom loses electrons, it becomes a cation (positively charged), whilst non-metals gain electrons to become anions (negatively charged).

Ionic bonding happens when these oppositely charged ions attract each other - it's like magnetic attraction but with electrons. You'll typically see this in compounds made from metals and non-metals, where the metal transfers electrons to the non-metal so both can achieve a full outer shell.

Quick tip: Group 1 and 2 metals love losing electrons, whilst Group 6 and 7 non-metals are keen to gain them. Group 0 elements don't bother with ionic bonding because they already have full outer shells!

Covalent and Metallic Bonding

Covalent bonds form when atoms share electrons rather than transferring them completely. You'll find these in most non-metal compounds, and they can be single, double, or triple bonds depending on how many electron pairs are shared.

The shared electrons are attracted to both atomic nuclei, making covalent bonds surprisingly strong. These bonds create everything from tiny molecules like water to massive structures like diamond.

Metallic bonding is quite different - imagine a sea of electrons floating around positively charged metal ions. These delocalised electrons aren't tied to any particular atom and can move freely around the metal structure, which explains why metals conduct electricity so well.

Remember: Covalent = sharing electrons, Metallic = sea of free electrons, Ionic = transferring electrons completely.

Properties of Ionic Compounds

Ionic compounds have some pretty distinctive characteristics that make them easy to spot. They typically have high melting and boiling points because those electrostatic forces between ions need loads of energy to break apart.

Here's something interesting: ionic compounds only conduct electricity when molten or dissolved in water. When solid, the ions are locked in place, but heating or dissolving frees them up to carry electrical charge.

The ions arrange themselves in a regular, closely packed pattern called an ionic lattice. This organised structure gives ionic compounds their characteristic properties and often makes them form crystals.

Exam tip: Remember that solid ionic compounds don't conduct electricity - the ions need to be free to move!

Giant Covalent Structures and Small Molecules

Giant covalent structures like diamond and graphite are absolutely massive networks of covalently bonded atoms. Most don't conduct electricity because there are no free charged particles floating about (graphite's the exception here).

Let's look at carbon's different forms: Diamond has four bonds per carbon atom, making it incredibly hard. Graphite only has three bonds per atom, arranged in slippery layers with delocalised electrons that conduct electricity. Graphene is basically one layer of graphite - super strong and great for electronics.

Small covalent molecules behave quite differently. They're usually gases or liquids at room temperature because the forces between molecules are weak, even though the bonds within each molecule are strong.

Key point: Don't confuse bonds within molecules (strong) with forces between molecules (usually weak)!

Metallic Properties and Fullerenes

Metals are brilliant conductors of heat and electricity thanks to those free-moving delocalised electrons. They also have high melting points and stay solid at room temperature because of strong electrostatic attractions.

Most pure metals are malleable (you can hammer them into shapes) because the layers of atoms can slide over each other. Alloys are different though - mixing different sized atoms distorts the layers, making them much harder.

Fullerenes are fascinating carbon molecules that form hollow spheres or tubes. These structures, made from hexagonal rings of carbon atoms, are used in everything from electronics to drug delivery systems because of their unique properties.

Cool fact: Fullerenes can trap other molecules inside their hollow structure, making them perfect for targeted drug delivery!